Support is requested to establish a predoctoral training program in Chemical and Structural Biology (CSB) at the University of California, Irvine (UCI). Over the past several years, UCI has hired faculty in Chemical Biology, which now is recognized here at UCI and elsewhere as a formal subdiscipline in Chemistry. Parallel to the growth in Chemical Biology has been substantial growth in Structural Biology, which includes protein crystallography, NMR spectroscopy, and computational biology. Several of the training faculty associated with this proposed program are located in the relatively new (10 years old) Natural Sciences 1 and nearby Natural Sciences 2 buildings. This, together with the open lab environment present in these buildings, has substantially increased interactions between students, postdocs, and faculty, fostering new and productive collaborations. The direct outcome of this parallel growth in Chemical and Structural Biology has been substantial changes in the UCI Chao Comprehensive Cancer Center. Early on, Prof. Poulos was Director of the Structural Molecular Biology Program in the Cancer Center. Over the years, however, more chemists joined the Cancer Center and it became apparent that the scope of research in the Structural and Molecular Biology Program no longer was limited to structural biology. It thus was decided to change the name and membership of the Program and bring in a Co-Director, Prof. Weiss, who represents the Dept. of Chemistry. This reorganization substantially increased collaborative efforts between Chemists and Biologists and resulted in several joint appointments. In addition, more and more graduate students were attracted to UCI's Chemical and Structural Biology Programs. This further resulted in the development of new courses that are taught primarily by Chemical and Structural Biologists. In effect, UCI already has a partially developed program in Chemical and Structural Biology and the purpose of this training grant is to formalize this program to continue to provide specific training at the Chemistry/Biology interface and to provide predoctoral students interested in Chemical and Structural Biology research with a formal training environment. This training grant will provide support for up to seven predoctoral trainees per year (with a 25% match from UCI's Graduate Division), starting in their second year, and offering continuous support for up to three years. Given the strength of structural biology here at UCI, and the many existing collaborations between chemists and structural biologists, we believe that a training program in CSB would best match our strengths. Additionally, many of our training faculty have collaborations throughout UCI, which include immunologists, engineers, cancer biologists, virologists, etc. Therefore, students in the CSB Program will not only have opportunities to interact with other CSB interested individuals, but the opportunity to interact with UCI research groups not specifically focused on chemistry or structural biology across campus.